To cite this article: Wijnen JCF, van de Riet IR, Lijfering WM, van der Meer FJM. Metformin use decreases the anticoagulant effect of phenprocoumon. J Thromb Haemost 2014; 12: 887-90.Summary. Background: Anticoagulant therapy with vitamin K antagonists (VKAs) is affected by interaction of the VKAs with a large number of other drugs. Although metformin is generally not considered to interact with VKAs, we observed a decrease in INR after starting metformin treatment in patients using the VKA phenprocoumon. Objectives: To investigate the influence of metformin use on the dosage of phenprocoumon and INR in stably anticoagulated patients. Patients: We used the database of the Anticoagulation Clinic Leiden for this study. In a population of 369 patients screened, 27 consecutive patients using phenprocoumon were prescribed metformin during the study period (1 January 2007 to 1 March 2009), without use of other concomitant medications or medical interventions that could influence the INR. Results: The mean phenprocoumon dosage increased from 2.13 to 2.37 mg per day within 6 weeks (mean increase, 0.23 mg; 95% CI, 0.12-0.34) and 2.49 mg per day within 3 months (mean increase, 0.36 mg; 95% CI, 0.24-0.48) after starting metformin. The mean INR decreased from 2.88 to 2.26 (mean decrease, 0.63; 95% CI, 0.41-0.85) within 6 weeks and 2.54 (mean decrease, 0.35; 95% CI, 0.24-0.48) within 3 months after starting metformin. Conclusions: This study shows that clinicians should be aware that metformin treatment may lead to an increased optimal dosage of phenprocoumon.

et al. Br J Surg 2010;97:650-6.Conclusion: There are no differences between sclerotherapy results in patients treated for truncal varices with foam sclerotherapy regardless of whether compression therapy after the procedure is used for 1 or 5 days.Summary: There are no data on the optimal bandaging regimen after foam sclerotherapy for truncal varices. In Great Britain, 80% of the members of the Vascular Society of Great Britain and Ireland responding to a questionnaire, and who treated patients with sclerotherapy, indicated they used compression bandages, and 90% subsequently used compression stockings after compression bandaging. Duration of treatment ranged from 1 to 7 days for initial bandages, with compression stockings used for 7 to 14 days, with some surgeons recommending compression stockings for up to 3 months. The authors sought to determine whether duration of bandaging could be reduced after foam sclerotherapy for truncal varices.Patients with primary uncomplicated varicose veins were randomized after foam sclerotherapy treatment to wearing compression bandaging for 24 hours or 5 days. In each case after compression bandages were removed, thromboembolism deterrent (TED) stockings then used for a total of 14 days of compression after foam sclerotherapy. The primary end point of the study was the 6-week Aberdeen Varicose Vein Severity Score (AVVSS) and Buford pain score. The study randomized 124 legs, of which 61 were randomized to 24 hours of compression bandaging and 63 to 5 days of compression bandaging. Venous occlusion rates at 6 weeks were 90% and 89%, respectfully (P ϭ .842). There were no differences in phlebitis after 2 weeks (P ϭ .445), skin discoloration after 6 weeks (46% vs 40%; P ϭ .546). There were no differences between groups in the AVVSS from baseline to 2 weeks (-0.29 vs -0.80; P ϭ .717) or to 6 weeks (-5.89 vs -5.14; 95% confidence interval [CI] for the difference, -3.29 to 1.8; P ϭ .563). There were also no differences between groups in changes in the Buford pain score from baseline to 2 weeks (-9.04 vs -2.80, P ϭ .248) or to 6 weeks (-17.32 vs -8.46; 95% CI for the difference, -19.06 to 1.33; P ϭ .088). Finally, the two groups also did not demonstrate any differences in changes in the Short Form-36 score from baseline to 6 weeks (2.02 vs. 1.74; P ϭ .903).Comment: Foam sclerotherapy is replacing liquid sclerotherapy as the preferred method of sclerotherapy for patients with truncal varicosities. Compression after treatment is essential to optimal results. However, as the authors point out with respect to foam sclerotherapy, the optimal duration of compression after treatment has not been adequately studied. This study is good news for patients. Compression bandages are not comfortable, and the results indicate that 24 hours of compressive bandaging, followed by a TED stocking for a total of 2 weeks, is just as efficacious as 5 days of compressive bandaging, followed by a TED stocking for a total of 2 weeks. The study provides practical guidance for post-therapy bandaging of patients...

PurposeThe purpose of the study is to determine the immediate and long-term effect of statins on coagulation in patients treated with vitamin K antagonists (VKAs).MethodsWe selected patients on VKAs of two Dutch anticoagulation clinics who initiated treatment with a statin between 2009 and 2013. Patients who initiated or stopped concomitant drugs that interact with VKAs or were hospitalised during follow-up were excluded. The VKA dosage (mg/day) after statin initiation was compared with the last VKA dosage before the statin was started. Immediate and long-term differences in VKA dosage (at 6 and 12 weeks) were calculated with a paired student t test.ResultsFour hundred thirty-five phenprocoumon users (mean age 70 years, 60 % men) and 303 acenocoumarol users (mean age 69 years, 58 % men) were included. After start of statin use, the immediate phenprocoumon dosage was 0.02 mg/day (95 % CI, 0.00 to 0.03) lower. At 6 and 12 weeks, these phenprocoumon dosages were 0.03 (95 % CI, 0.01 to 0.05) and 0.07 mg/day (95 % CI, 0.04 to 0.09) lower as compared with the dosage before first statin use. In acenocoumarol users, VKA dosage was 0.04 mg/day (95%CI, 0.01 to 0.07) (immediate effect), 0.10 (95 % CI, 0.03 to 0.16) (at 6 weeks), and 0.11 mg/day (95 % CI, 0.04 to 0.18) (after 12 weeks) lower.ConclusionsInitiation of statin treatment was associated with an immediate and long-term minor although statistically significant decrease in VKA dosage in both phenprocoumon and acenocoumarol users, which suggests that statins may have anticoagulant properties.

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